Processors, memory devices, imagers and other types of microelectronic devices are often manufactured on semiconductor workpieces or other types of workpieces. In a typical application, several individual dies (e.g., devices) are fabricated on a single workpiece using sophisticated and expensive equipment and processes. Individual dies generally include an integrated circuit and a plurality of bond-pads coupled to the integrated circuit. The bond-pads provide external electrical contacts on the die through which supply voltage, signals, etc., are transmitted to and from the integrated circuit. The bond-pads are usually very small, and they are arranged in an array having a fine pitch between bond-pads. The dies can also be quite delicate. As a result, after fabrication, the dies are packaged to protect the dies and to connect the bond-pads to another array of larger terminals that is easier to connect to a printed circuit board.
Conventional processes for packaging dies include electrically coupling the bond-pads on the dies to an array of pins, ball-pads, or other types of electrical terminals, and then encapsulating the dies to protect them from environmental factors (e.g., moisture, particulates, static electricity, and physical impact). In one application, the bond-pads are electrically connected to contacts on an interposer substrate that has an array of ball-pads. FIG. 1A, for example, schematically illustrates a conventional packaged microelectronic device 10 including an interposer substrate 20 having an array of external contacts 22, a microelectronic die 30 attached to the interposer substrate 20, and a plurality of wire-bonds 32 electrically coupling the die 30 to the external contacts 22 of the interposer substrate 20. The die 30 is attached to the interposer substrate 20 with a generally flexible adhesive material 50 (e.g., epoxy, tape, etc.). The die 30 has been encapsulated with a casing 60 to protect the die 30 and corresponding wire-bonds 32 from environmental factors.
One drawback of this conventional arrangement is that stresses within the device 10 can cause the device 10 to bow or warp after encapsulation. FIG. 1B, for example, is a view of the device 10 after the device has bowed, with the amount of bowing highly exaggerated for purposes of illustration. The bowing can be caused by several factors, such as an asymmetrical stress distribution within the device caused by the difference between the coefficients of thermal expansion of the interposer substrate 20, the microelectronic die 30, and the casing 60. The generally flexible or compliant adhesive material 50 moves along with the substrate 20 and die 30, and does little or nothing to prevent the bowing or warpage of the device 10. The warpage can cause the solder links between the interposer substrate 20 and a printed circuit board (not shown) to which the interposer substrate 20 is attached to fail, and/or can cause the die 30, the interposer substrate 20, and/or the casing 60 to delaminate. Such failures can cause electrical shorts that render the device 10 defective. Accordingly, there is a need to improve the robustness of microelectronic devices.